Visa Application with only 4 months valid Thai entry permit in passport

Hello, We are South African living in Thailand ( Koh Phangan) on retirement Thai resident permit, expiring Dec 2015. We are passing through BKK in August on our way to Yunnan, 1) is 3 days long enough to process? 2) we will only have 4 months valid Thai resident permit before renewal, is that OK? Please advise before we book flights and hotels. Regards pam